The oneness of the Church refers to its unity. In John 17:23, the high priestly prayer of Christ, Jesus asks God to make his Church one as they are one. In direct opposition to this the Church has been fragmenting since day one, however some of the better ecumenical movements of the 20th and 21st century are seeking to combat this situation. The WCC is but one, albeit a mixed, example.
The next predicate, holy, refers to the ongoing process of the Church’s sanctification. The Church is made to look like and be like he whom she follows, Jesus.
The catholicity of the church points to the true faith of the universal Church throughout history. Just like one cannot pin down and definitively identify the entire truth of a singular individual, so the Church’s Truth cannot be propositionally identified once and for all time. This is in direct connection to the fact that Jesus, a person who is God, is the Church’s Truth and thus is beyond full epistemic comprehension. Yet, this Truth is nonetheless known through faith and relationship with Christ and his Church.
The last marker, apostolic, calls the Church to seek to live in continuity with the original faith of the Apostles. The Church is a missionary church and its message is universal. While this is true, the Church’s faith is also historical and immanent. The Church has and will never be able to access orthodoxy in some transcendent realm. This does not mean that the Church should give into post-modern sophistry, but rather that she should humbly and repentantly seek the correction of the Spirit, who may come in ways totally unexpected. Possibly through the voice of the gay man in their midst or possibly, and this is even more frightening for me, through the fundamentalist. Put simply, the Church’s message has always been in some ways culturally syncretistic and yet the Church has always striven for a purified faith that is in direct fidelity to its source in the life of God as seen most definitively in the life of Jesus Christ.
The four marks of the Church are often understood as statements of faith explaining her identity. This is true and yet obviously false. The Church has always fallen short of these fours marks in its manifestation. Thus, the four marks are also a call to an unfaithful Church to come back to its identity and mission.
In addition, I believe that the four marks of the Church are vastly important for linguistically demarcating the inter-ecclesial discussion that should unfold concerning the Church’s identity and mission. While this is the case, they are not the end of the discussion. Rather, they are the beginning and a beginning that is dependent on many other factors for a healthy and proper ecclesiology.
From my perspective the Church has always considered itself and its mission too narrowly and often from a place of power that is in direct opposition to the subjective position of its Lord. In light of this while the markers are helpful identifiers for where to begin, I believe that the Truth of the Church is only likely to be uncovered as its existential modalities and operations are aligned with that of the Spirit’s in the world, which is often found among the least of these, instead of among the most powerful. In other words, praxis constrains and defines orthodoxy.